Fluid-blast piston arrangement and contact structure for circuit interrupters



Oct. 26, 1965 R. E. FRIEDRICH 3,214,549

FLUID-BLAST PISTON ARRANGEMENT AND CONTACT STRUCTURE FOR CIRCUITINTERRUPTERS Filed May 2, 1962 s Sheets-Sheet 1 IRELATIVELY 5 HIGH 2PRESSURE GAS Fig. I.

' lNVENTOR Robert E. Friedrich ATTOR N EY Oct. 26, 1965 R. E. FRIEDRICH3,214,549

FLUID-BLAST PISTON ARRANGEMENT AND CONTACT STRUCTURE FOR CIRCUITINTERRUPTERS Filed May 2, 1962 5 Sheets-Sheet 2 a a l I L I Fig.2.

Oct. 26, 1965 R E. FRIEDRICH 3,214,549

FLUID-BLAST PI STON ARRANGEMENT AND CONTACT STRUCTURE FOR CIRCUITINTERRUPTERS Filed May 2, 1962 5 Sheets-Sheet 3 Fig.4.

9 4 4 a H m 1 n S 9w .m 3 e T h MS T N 5 O C Oct. 26, 1965 R. E.FRIEDRICH FLUID-BLAST PISTON ARRANGEMENT AND STRUCTURE FOR CIRCUITINTERRUPTERS Filed May 2, 1962 Fig.5.

Oct. 26, 1965 R. E. FRIEDRICH 3,214,549

FLUID-BLAST PISTON ARRANGEMENT AND CONTACT STRUCTURE FOR CIRCUITINTERRUPTERS 5 Sheets-Sheet 5 Filed May 2, 1962 Fig.6.

United States Patent 3,214,549 FLUID BLAST PISTON ARRANGEMENT ANDCONTACT STRUCTURE FOR CIR- CUIT INTERRUPTERS Robert E. Friedrich,Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, EastPittsburgh, Pa., a corporation of Pennsylvania I Filed May 2, 1962, Ser.No. 191,957

Claims. (Cl. 200-148) This invention relates to circuit interrupters ingeneral, and, more particularly, to circuit interrupters of the type inwhich an arc-extinguishing fluid, such as a liquid or a gas, is injectedinto the arcing space during the opening operation to effect areextinction.

A general object of the present invention is to provide an improvedsimplified-type of circuit interrupter in which highly-effectivearc-extinguishing action is obtained without the reliance of an externalhigh-pressure fluid source.

A more detailed object of the present invention is the provision of animproved circuit interrupter of the selfgenerated fluid-pressure type inwhich biasing means, such as a compression spring, is employed toactuate a suitable piston, or puffer structure to inject a blast offluid, such as gas, under pressure into the arc to effect the extinctionthereof.

In United States Patent 2,933,575, issued April 19, 1960, to Benjamin P.Baker, and assigned to the asignee of the instant application, there .isdisclosed and claimed a circuit interrupter of the puffer type, in whicha piston is secured to, and movable with the movable contact structureand actuated by a biasing means, such as a compression spring. In theaforesaid patent, a conducting crossbar, bridging a pair ofserially-related units, is effective to charge the compression springsassociated with the two interrupting units during the closing stroke,and also to effect contact-engaging movement. During the openingoperation, the cross-bar moves downwardly, being actuated vertically byan insulating lift rod, and permits the biasing springs to actuate theaforesaid piston structures to inject an arc-extinguishing gas' into thedrawn arcs established within the interrupting units.

It is a further object of the present invention to improve upon thepuifer structure of the aforesaid Baker patent rendering it moreeffective, and, in addition, adapting the same to the use of a shuntingresistor for lowering the rate of rise of the recovery-voltagetransient.

Still a further object of the present invention is the provision of animproved puffer-type circuit interrupter in which the blast ofarc-extinguishing fluid, such as a gas, is ejected not only toward theestablished arc, but also through the movable tubular contact and towardthe isolating gap to assist thereby in the interruption of theresidual-current are, when a shunting resistance is employed.

additional object of the invention is to provide an improved contactstructure for a fluid-blast circuit interrupter.

Further objects and advantages will readily become apparent upon readingthe following specification, taken in conjunction with the drawings, inwhich:

FIGURE 1 is a vertical sectional view taken through a three-phase,three-pole circuit interrupter embodying the principles of the presentinvention, the contact structure being illustrated in the closed-circuitposition;

FIG. 2 is a vertical sectional view taken substantially along the lineII-II of FIG. 1;

FIG. 3 is an enlarged vertical sectional view taken through one of theimproved puffer-type interrupting units of the present invention, thecontact structure being illustrated in the closed-circuit position;

3,214,549 Patented Oct. 26, 1965 FIG. 4 is a view similar to that ofFIG. 3, but illustrating the dispositon of the several parts at anintermediate point in the opening operation;

FIG. 5 is a top plan view of the breaker unit of FIG. 1 illustrating, inplan, the interrupter and resistor locations; and,

FIG. 6 is a vertical sectional view taken through a modified-type ofinterrupting unit, the several parts being shown at an intermediatepoint in the opening operation.

Referring to the drawings, and more particularly to FIG. 1 thereof, thereference numeral 1 generally designates a three-phase, three-polefluid-type circuit interrupter; Although the arc-extinguishing fluid,for purposes of illustration, is assumed to be gas in the particularexample shown, nevertheless it will be apparent to those skilled in theart that certain aspects of the present invention are applicable toother types of fluid-blast circuit interrupters utilizing differentarc-extinguishing fluids than gas, for instance liquid, such as oil. Theterm fluid as employed in the appended claims is intended to cover anyarc-extinguishing fluid, such as gases, liquids, vapors and sprays.

As shown in FIG. 5, the circuit interrupter 1 includes three pole-unitsA, B and C disposed within a single tank structure 2. Each pole-unit A,B, or C includes a pair of serially-related arc-extinguishing units 3electrically interconnected by a conducting bridging member 4, actuatedvertically, in a reciprocal manner, by an insulating liftrod 5. Theupper end of each of the three lift-rods 5 is mechanicallyinterconnected to a horizontally reciprocally movable operating rod 6(FIG. 2) which is actuated by a suitable mechanism, not shown, disposedwithin a mechanism compartment 7 From the foregoing description, it willbe apparent that during the opening operation suitablemechanism,disposed within the mechanism compartment 7, is effective to transmitmotion through the operating rod 6, and, by suitable connectingmechanism effect downward opening movement of the several lift-rods 5and consequent downward simultaneous opening movement of the threecrossbars 4.

As illustrated in FIGS. 1 and 2 of,the drawings, preferably thearc-extinguishing units 3 are threadedly secured and fixedly clamped tothe interior ends of terminal bushings 8, 9, 10, 11 and 12, 13 extendingupwardly through an upper tank cover portion 14 and fixedly securedthere'- to. Preferably current transformers 15 are employed formeasuring the current flow'through thecircuit interrupter 1 and forrelaying functions, as well known by those skilled in the art.

With reference to FIGS. 3 and 4 of the drawings, which more clearlyillustrate the operation of the circuit-interrupting unit 3, it will beapparent that each unit 3 includes a tubular vented stationary contactstructure 16 cooperable with a movable tubular contact 17.

As shown, the stationary contact 16 has an upper enlarged portion 16a,and a lower relatively-reduced portion 16b. In addition, ventingopenings are provided in the upper portion of the enlargement 16a sothat the stationary contact 16 is freely vented.

The movable tubular contact 17 includes an annular outer set or clusterof relatively long circumferentiallydisposed flexible main contactfingers 17a and an annular inner set or cluster of relatively shortcircumferentiallydisposed flexible arcing fingers 17b. As shown, themain contact fingers 17a engage the external surface of the enlargedportion 16a, whereas the relatively short arcing fingers 17b engage thereduced portion 16b of the stationary contact 16. The arrangementfunctions to separate the movable main contact fingers 17a from theenlarged portion 16a prior to separation of the movable arcing finger16b from the lower reduced neck portion 16b of the stationary contact 16so that the arc is established adjacent the lower extremity 16d of thestationary contact, the purpose for which will be more apparenthereinafter;

The movable contact 17 has fixedly secured thereto, and movabletherewith, an annular conducting piston portion 18 reciprocally movablewithin an operating cylinder 19, and biased downwardly in an openingdirection by-a battery of compression springs 20. As shown, theconducting piston portion 18 supports the two sets of movable flexiblearcing fingers 17a, 17b.

The compression springs 20 seat at their upper ends against a relativelyfixed apertured partition plate 21, and seat at their lower ends againsta spring plate 22 secured to, and movable with the lower extremity 170of the movable tubularcontact 17.

As shown in FIG. 3, the conducting cross-bar 4 abuts the lower side22a-of the spring plate 22 and forces the same upwardly, therebycharging the battery of compression springs 20 and effecting contactengagement between the movable tubular contact structure 17 and therela- 'tively stationary contacts 16. A suitable flange portion 23 of"the cylinder 19 provides a stop, and serves the function of halting thedownward opening travel of the movable spring plate 22, permittingthereby the separation between thecontact portions 4a of the conductingcross-bar 4*andthe lower surface 22a of the spring plate 22. Thedottedlines 25 in FIGS. 1 and 2 illustrate the open-circuitposition ofthe conducting cross-bar 4.

Preferably, the apertured partition plate 21 is at least 'partlyformedof a suitable conducting material, and not 'only effects a guidingfunction, but also serves to transmit current from a shunting impedancemeans 26, such as a resistor unit- 27, electrically interconnecting thepartition plate 21 with the relatively stationary contact structure 16.As a result, during the opening operation, the downward opening movementof the movable tubular contact 17 Y away from the tubularventedstationary contact 16 draws an are 28 (FIG. 4), which is shuntedby the impedance means 26. Aswell known by those skilled in the art, theshunting impedance means 26 facilitates the interruption-ofthe maincurrent arc 28 (FIG. 4) and forces the current through the interrupterunit 3 to pass through the resistor unit 27, thereby decreasing themagnitude of the current and also improving the power factor.

The residual-current are 29 (FIG. 6) is established between the end 4aof the conducting cross-bar 4 and the lower surface 22a ofthe springplate 22, constituting thereby relatively separable disconnectingcontacts. This are 29 is easily interrupted since it is of smallamperage, and the current and voltage are substantially in phase.

During the closing operation, the operating mechanism disposed. withinthe'mechanism compartment 7 is effective to cause horizontalmovement ofthe operating rod .6 and, consequently, upward closing travel'of'theseveral lift-rods 5, thereby eifectingclosing of the contact structures16, 17 and simultaneously causing charging of the several compressionspringsZO;

It will be noted that particularly effective gas-flow conditions existduring the opening operation by the gas flow passing upwardly throughthe tubular relatively stationary contact 16 and out throughventopenings. 16c associated therewith. The gas-flow conditions areindicated by the .arrows30 in FIG. 4 of the drawings.

With reference to FIG. of the drawings, it will be observed thatparticularly advantageous locations of the interrupting units 3 andresistor columns 27 are obtained by the illustrated construction. Theresult is compactness in size and a minimum lateral dimension of theseveralparts. Where a suitable high-dielectric-strengtharc-extinguishing gas, such as sulfur-hexafluoride (SP gas, isemployed,the spacing between the high-voltage parts and the grounded tankstructure 2 may be a minimum. Moreover, it will be noted that droppingof a lower portion 2a of the tank 2' from the upper cover portion 14thereof permits a ready inspection of the several units. By disposingthe three pole-units A, B and C within a single tank structure 2foundation space, required for the circuit interrupter 1, is therebyminimized.

FIG. 6 illustrates a modification of the invention in which the movabletubular contact 31 is vented throughout its entire length. As a result,during the opening operation, as illustrated in FIG. 6, the gas flow maypass downwardly through the lower vent opening 32 and facilitateextinction of the residual current arc 29. This has the advantage ofutilizing the generated gas under pressure for two functions, firstinterrupting the main current are 23, as indicated by the arrows 34, andsecondly, causing a downward flow of gas, as indicatedbythe arrows 35,toward the residual-current are 29, which is, therefore, more quicklyinterrupted.

It will be noted that again the movable contact structure 31 has a setof' circumferentially-disposed main contact fingers 31a, and, inaddition, an outer longer set of arcing contact fingers 31b. In thisembodiment of the invention the relatively stationary. contact structure33 has straight wall portions, and the movable main and arcing sets offingers 31a, 31b are reversed in location,- with respect to FIG. 3, sothat the movable arcing fingers 3112 will separate last from thestationary contact 33. The arc, as before, will be drawnat the lowerextremity 33a of the stationary contact 33 with at least part of theexhaust gas passing through the stationary tubular contact 33 in themanner illustrated by the arrows 34..

Although the invention has been described in connec tion with a suitablearc-extinguishing gas, such as sulfurhexafluoride (SP gas, providedwithin the space 36 within the tank structure 2,,it is to be clearlyunderstood that other arc-extinguishing mediums may be employed. Forexample, the circuit'interrupter 1 may be utilized with a suitablearc-extinguishing liquid, such as circuitbreaker oil, instead of thedescribed gas.. In this case;

the annular piston 18 would function to inject a blastofarc-extinguishing oil under pressure into the main cur.- rent are 28 andthereby effect the rapi-dextinction thereof. As will be obvious, the useof a gas, such as sulfurhexafluoride (SP gas, instead of oil resultsin'a lighter construction for the circuit interrupter with less Weightthereby imposed upon the framework 37 of the circuit interrupter 1.

The invention is particularly adapted for a mediumrange interruptingcapacity of say, for example, 5000 mva. at voltages up to and including.161 kv; It will be obvious, that by a suitable dimensioning of theparts, higher powers may be interrupted.

Although there have been illustrated and described specific structures,it is to be clearly understood that the same were merely for the purposeof illustration, and that changes and modifications may readily be madetherein by those skilled in the art, without departing from the spiritand scope of the invention.

I claim as my invention:

1. A fluid blast circuit interrupter including a grounded tankstructure, a pair of terminal bushings extending into said grounded tankstructure and carrying a pair of arcextinguishing units at theirinterior ends, a conducting cross-bar for electrically interconnectingthe units, each arc-extinguishing unit including a. relativelystationary contact and a cooperable movable contact tubular throughoutits entire length, a relatively stationaryapertured partition platehaving at least a conducting portion, impedance means electricallyinterconnecting the conducting portion of said apertured partition platewith said relatively stationary contact, an annular piston see cured toand movable with said movable contact, the relatively stationary andmovable contacts cooperating to establish a main current arc, the end ofthe cross-bar cooperating with the movable contact to establish a resi:dual-current arc, biasing means for biasing the movable contact towardthe open position and said annular piston in a fluid-injectingdirection, and said piston forcing fluid longitudinally through thetubular movable contact into the two arcing regions, whereby the fluidblast is injected toward the residual-current are as well as toward themain-current arc.

2. The combination in a three-phase three-pole fluidblast circuitinterrupter of a single tank structure, three pairs of terminal bushingsextending into the tank structure, the tank structure being grounded,six arc-extinguishing units secured to the interior ends of the threepairs of terminal bushings, three pairs of cross-bars, operating meansfor simultaneously effecting the opening and closing movement of thethree cross-bars, each arcextinguishing unit including relativelyseparable contacts each having a tubular portion, one of said relativelyseparable contacts carrying an annular piston member and being movable,said one movable contact being tubular throughout its entire length,spring means for biasing the annular piston member and said onerelatively movable contact in a downward opening direction, impedancemeans electrically interconnecting the other of the relatively separablecontacts with an external side surface of the first said relativelyseparable contacts to facilitate the interruption of the main-currentarcs, separation of the ends of the conducting cross-bars from said oneseparable contacts drawing residual-current arcs at the lower ends ofeach of the arc-extinguishing units, and the movement of each annularpiston member in the opening direction causing a flow ofarc-extinguishing fluid to pass through the respective movable contactto flow toward the residual-current are as well as toward the maincurrent arc.

3. A fluid-blast circuit interrupter including a relatively stationarytubular contact having an exhaust opening therethrough, cooperablemovable contact structure including a relatively long set ofcircumferentially-disposed flexible arcing contact fingers and aninwardly disposed shorter set of circumferentially-disposed flexiblemain contact fingers, conducting movable piston means carrying said twosets of contact fingers, the two sets of contact fingers engagingconductively the external sides of said relatively stationary tubularcontact, the arrangement functioning to separate the main contactfingers first and then subsequently the arcing contact fingers from therelatively stationary tubular contact, a rearwardly-disposed conductingtubular contact tube having inlet openings in the side wall thereof,means defining an operating cylinder within which said movable pistonmeans moves, fluid injected by said piston means entering said inletopenings and into the arcing region, and at least a portion of saidinjected fluid exhausting through said exhaust opening in the relativelystationary tubular contact.

4. A fluid-blast circuit interrupter including a relatively stationarytubular contact freely vented and having an exhaust openingtherethrough, said relatively stationary contact having a tubularenlarged portion and a smaller tubular end portion, cooperable movablecontact structure including a relatively long annular cluster ofcircumferentially-disposed flexible main contact fingers and an inwardlydisposed annular cluster of circumferentially-disposed flexible shorterarcing contact fingers, conducting movable piston means carrying saidtwo clusters of contact fingers, the two sets of contact fingersengaging conductively the external sides of said relatively stationarytubular contact on the two different diameter portions thereof, thearrangement functioning to separate the main contact fingers first andthen subsequently the arcing contact fingers from the relativelystationary tubular contact, a rearwardly-disposed conducting tubularcontact tube having inlet openings in the side wall thereof, meansdefining an operating cylinder within which said movable piston meansmoves, fluid injected by said piston means entering said inlet openingsand into the arcing region, and at least a portion of said injectedfluid exhausting through said freely vented exhaust opening in therelatively stationary tubular contact.

5. A fluid-blast circuit interrupter including an arcextinguishing unit,said arc-extinguishing unit including a relatively stationary contactand a cooperable movable contact separable to establish a main-currentarc, said movable contact being tubular throughout its entire length,impedance means electrically shunting said contacts, means defining anoperating cylinder, said movable contact carrying an annular pistontherewith, the movable tubular contact having side openings, biasingmeans for biasing the movable contact toward the open position and saidannular piston in a fluid-injecting direction within the operatingcylinder, a conducting operating member making separable contact withsaid movable contact and cooperablc therewith to establish aresidual-current arc, and the fluid blast being injected toward theresidualcurrent are as well as toward the main current are.

References Cited by the Examiner UNITED STATES PATENTS 1,336,069 4/20Conrad 200- 2,032,241 2/36 Whitehead 200166 2,037,544 4/36 Seaman200-166 2,459,599 1/49 Strom 200148 2,757,261 7/56 Lingal et al. 200-4482,786,922 3/57 Stumpfhaus 200-466 2,933,575 4/60 Baker 200-148 KATHLEENH. CLAFFY, Primary Examiner. BERNARD A. GILHEANY, Examiner.

1. A FLUID BLAST CIRCUIT INTERRUPTER INCLUDING A GROUNDED TANKSTRUCTURE, A PAIR OF TERMINAL BUSHINGS EXTENDING INTO SAID GROUNDED TANKSTRUCTURE AND CARRYING A PAIR OF ARCEXTINGUISHING UNITS AT THEIRINTERIOR ENDS, A CONDUCTING CROSS-BAR FOR ELECTRICALLY INTERCONNECTINGTHE UNITS, EACH ARC-EXTINGUISHING UNIT INCLUDING A RELATIVELY STATIONARYCONTACT AND A COOPERABLE MOVABLE CONTACT TUBULAR THROUGHOUT ITS ENTIRELENGTH, A RELATIVELY STATIONARY APERTURED PARTITION PLATE HAVING ATLEAST A CONDUCTING PORTION, IMPEDANCE MEANS ELECTRICALLY INTERCONNECTINGTHE CONDUCTING PORTION OF SAID APERTURED PARTITION PLATE WITH SAIDRELATIVELY STATIONARY CONTACT, AN ANNULAR PISTON SECURED TO AND MOVABLEWITH SAID MOVABLE CONTACT, THE RELATIVELY STATIONARY AND MOVABLECONTACTS COOPERATING TO ESTABLISH A MAIN CURRENT ARC, THE END OF THECROSS-BAR COOPERATING WITH THE MOVABLE CONTACT TO ESTABLISH ARESIDUAL-CURRENT ARC, BIASING MEANS FOR BIASING THE MOVABLE CONTACTTOWARD THE OPEN POSITION AND SAID ANNULAR PISTON IN A FLUID-INJECTINGDIRECTION, AND SAID PISTON FORCING FLUID LONGITUDINALLY THROUGH THETUBULAR MOVABLE CONTACT INTO THE TWO ARCING REGIONS, WHEREBY THE FLUIDBLAST IS INJECTED TOWARD THE RESIDUAL-CURRENT ARC AS WELL AS TOWARD THEMAIN-CURRENT ARC.